1. Technical Field
The invention relates to a system, including a device, method and system alone or in combination, for providing data in a mobile device, which may be located in a vehicle or elsewhere.
2. Related Art
A demand has arisen for information and entertainment systems in which the driver of a vehicle is provided with traffic and navigation information and the passengers are provided with entertainment programs, such as audio or video broadcasts. These information and entertainment systems may be implemented in mobile devices, such as navigation systems, mobile radio receivers for receiving broadcasted audio signals, and television receivers for receiving broadcasted video and audio signals. However, the computing and memory limitations of these mobile devices, particularly those installed in vehicles, often make simultaneous provision of information and entertainment data impossible.
A navigation system generally includes a storage device in which program data, navigation data and voice data are made available. For example, in standard navigation systems, voice samples, which are used to output navigation instructions, may be provided on a removable storage device such as a compact disk (CD), or stored in a fixed storage device, such as the internal memory of the navigation system device. Navigation systems also generally include one or more processing devices that, while the vehicle is traveling, access the data in the storage device and process the data in real-time.
In order to store data, particularly voice data, in the storage device, data compression is usually required. The data compression may include a lower or higher degree of compression. Each degree of compression has associated problems. A higher degree of compression reduces the storage area needed to store the compressed data in the storage device, but generally requires a more complex method for encoding and decoding the data, and may require additional computing hardware. One example of a compression code with a higher degree of compression (a “high compression code”) is as MPEG audio layer 3 (MP3). When data is encoded with a high compression code, such as MP3, it may need to be decoded with a specialized piece of digital signal processing hardware. High compression codes, such as MP3 and those that comply with the ITU standard G.723, can achieve a significantly high degree of compression (for example, a compression factor of up to 10), which results in a data rate of approximately 10-32 kbit/s with the same reproduction quality. However, decoding the stored data requires a significant amount of calculation power and can only be accomplished using software in systems that have this calculation power. Hence, when high compression codes are used in a navigation system, additional hardware needs to be installed in the navigation system, or existing components need to be used by a plurality of applications in a time sharing arrangement. In many navigation systems, the navigation language cannot be mixed with MP3 data, such as music, because more than one decoding process needs to be established simultaneous.
In comparison, a lower degree of compression may allow for real-time processing of the data without using complex decoding hardware and/or software. However, using a lower degree of compression requires more storage space on the storage device to store the compressed data. One example of a compression code with a lower degree of compression (a “low compression code”) is adaptive delta pulse code modulation (ADPCM). When data is encoded with a low compression code, such as ADPCM, it may then be decoded using software, hardware, or a combination of hardware and software. Although the use of low compression codes, such as ADPCM, allows decoding in real-time by a processor such as the central processing unit (CPU) of a navigation system, the compression rates that can be achieved are comparatively low, currently about 64 kbit/s. Details of ADPCM, available from ITU-T recommendations G.726 and G.727, envision data rates of 16, 24, 32 and 40 kbit/s. According to the new ITU standard G.722 for broadband speech transmission based on a frequency range of 50 Hz to 7 kHz, which would result in normal PCM-technique to a data rate of 128 kbit/s, a compression to 64 kbit/s can be obtained.